SERPINC1 and hereditary antithrombin deficiency: Only few polymorphisms affecting SERPINC1 are described, most of them neutral, and those with missense consequences, such as that responsible for the Cambridge II variant has been associated with increased risk of venous thrombosis [2].Thus, practically all mutations or gross deletions affecting the coding or flanking regions of SERPINC1 cause antithrombin deficiency and are identified in 70–80% of patients with deficiency of this key anticoagulant [3,4].